解决`docker pull`被 reset 的问题

例如：

$ docker pull ubuntu:16.04
Trying to pull repository docker.io/library/ubuntu ... 
Get https://registry-1.docker.io/v2/library/ubuntu/manifests/sha256:dd7808d8792c9841d0b460122f1acf0a2dd1f56404f8d1e56298048885e45535: Get https://auth.docker.io/token?scope=repository%3Alibrary%2Fubuntu%3Apull&service=registry.docker.io: read tcp *.*.*.*:41348->50.17.62.194:443: read: connection reset by peer

原因：目测 50.17.62.194 被 TCP RESET 。

解决方法：

找到其它可用 IP ：

$ dig auth.docker.io

; <<>> DiG 9.10.4-P6-RedHat-9.10.4-4.P6.fc25 <<>> auth.docker.io
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 7119
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;auth.docker.io.			IN	A

;; ANSWER SECTION:
auth.docker.io.		60	IN	A	34.193.147.40
auth.docker.io.		60	IN	A	50.17.62.194
auth.docker.io.		60	IN	A	52.5.246.212

;; Query time: 130 msec
;; SERVER: *.*.*.*#53(.*.*.*.*)
;; WHEN: Tue Mar 07 11:03:29 CST 2017
;; MSG SIZE  rcvd: 91

改/etc/hosts强制 docker.io 相关的域名解析到其它可用 IP ：

# /etc/hosts
34.193.147.40 registry-1.docker.io auth.docker.io